There are [several documents] providing detailed upgrade instructions for various ]po[ versions.
This is explained in detail in the PO-Operations-Maintenance-Guide.
Basicly, you use the built-in PostgreSQL commands to backup and restore your database. There is a "wrapper page" in ]project-open[, but this page basicly calls the PostgreSQL commands:
To backup: pg_dump projop -c -O -F p -f c:/backup.YYYY-MM-DD.sql
To restore: psql -d projop -f c:/backup.YYYY-MM-DD.sql
These commands work both on Linux and Windows (CygWin shell). Please note that the "forward slashes" are being used in both cases.
Please note that the "restore" operation may write out a lot of error messages if you load a backup dump into an empty database. This is because the backup file contains SQL commands to delete the data in an existing database. You don't need to worry about these errors.
Installations using PostgreSQL 8.2 and earlier require frequent DB vacuums. The VM downloadable from SOURCEFORGE should be configured accordingly (see crontab).
Results are written into /var/log/postgres82/vacuumdb.log (or similar). First check this log file for any irregularities.
Next you want to check your /web/projop/log/error.log file for irregularities.
Other reasons for bad performance can be:
Low disk space
Extend/free disk space and /or use de-fragmentation tools